Forwarding traffic flow in intelligent resilient framework system

ABSTRACT

A method and member device for forwarding service messages in an Intelligent Resilient Framework (IRF) system and an IRF system. In the method, each member device in the IRF system is allocated to at least two virtual devices, and at least one stack link for each virtual device is configured in order to connect interface boards among different member devices. When it is determined according to a forwarding entry of an interface board in a first member device receiving a service message that the service message is to be transmitted to a second member device, the service message is forwarded via the at least one stack link configured for the virtual device of that interface board.

BACKGROUND

Intelligent Resilient Framework (IRF) technology uses cable to connectmultiple physical devices together to form a single logical device. Theresulting logical device is commonly referred to as an IRF system. Eachphysical device that constitutes the IRF system is called a memberdevice, and connections between member devices are known as stack links.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of an IRF system;

FIG. 2 is a schematic diagram illustrating a way of mapping a physicaldevice into multiple logical device;

FIG. 3 is a schematic diagram illustrating one possible composition ofan IRF system supporting VD technology;

FIG. 4 is a schematic diagram illustrating one possible composition ofan IRF system supporting VD technology in an example of the presentdisclosure.

DETAILED DESCRIPTION

As shown in FIG. 1, distributed devices 1 and 2 can form a logicaldevice by using stack links. The logical device, labeled “virtualdistributed device” in FIG. 1, is considered to be an IRF system. Aparticular control board is used as a primary control board of thelogical device, while other control boards are used as spare controlboards.

Virtual device (VD) technology virtualizes a physical device intomultiple logical devices. Each logical device is called a VD. Each VD isa stand-alone device from a user's point of view, having its ownindependently running routing processes, Layer 2 and Layer 3 protocols,forwarding entries and interfaces, etc. Also, each VD can add its usersseparately, perform independent reset and read its configuration files,all without affecting other VDs.

For a system that can support VD technology, a managing VD will firstlybe created when the system starts, which is usually designated as VD1 bydefault. Other VDs can then only be created and deleted under control ofthe managing VD. The managing VD is also responsible for managing theresources of other VDs.

When a VD is started, a group of necessary processes of the VD will alsobe started and isolated from those of other VDs. FIG. 2 is a schematicdiagram illustrating a way of mapping a physical device into multiplelogical devices. In the illustrated example, four VDs are created at aprimary control board. Interface boards are allocated to correspondingVDs. All VDs share a control plane network and a data plane network.However, the forwarding chip at an interface board only belongs to aparticular VD, that is, a forwarding chip in an interface board cannotbe used for issuing forwarding entries of other VDs except for the VD towhich it corresponds.

If the IRF and VD technologies are combined, then the VD is supported inthe IRF system. That is, the IRF system is built on the basis of amanaging VD (i.e., VD1) and virtualized to form a system as shown inFIG. 3. In this IRF system, stack links are responsible for providingthe control plane network and data plane network between member devices.

For the control plane network, a stack link is a path shared by all VDsfor transmission across member devices in the control plane. For thedata plane network, the forwarding chip of the interface board connectedto the stack link belongs to VD1. Consequently, VD1 only has its ownforwarding entries. Therefore, traffic flow of other VDs will bediscarded when it is to be transmitted through the stack link of VD1since no corresponding forwarding entry can be found. Hence, the stacklink does not have the ability to bear transmission across memberdevices in the data plane for all VDs.

Referring to FIG. 3, VD1 and VD2 are isolated in the data plane, and atraffic flow of VD2 cannot be transmitted from member device 1 to memberdevice 2 through the illustrated stack link. That is, because the stacklink is connected to an interface board of each member device thatcorresponds to VD1 and has no forwarding entries of VD2, the trafficflow transmission of VD2 across member devices can not be achieved onthe stack link that is connected to the interface board 1 correspondingto VD1 of either member device.

Consequently, a technical solution is provided as an example forforwarding traffic flow in an Intelligent Resilient Framework (IRF)system, that comprises: each member device of the IRF system isallocated to at least two virtual devices (VD) where the IRF systemcomprises at least two member devices. Multiple stack links areconfigured among interface boards of these member devices. For example,interface boards in the two different member devices belonging to thesame VD are connected by a stack link.

Thus, when an interface board of a member device receives a servicemessage from the VD corresponding to that interface board, forwardingentries of the interface board are checked. If the service message is tobe forwarded across member devices, the interface board is able toforward the service message to another member device through a stacklink connected to that interface board which corresponds to the VDsending the service message.

In the example of FIG. 4, there are stack links between interface boardsof different member devices allocated to a managing VD, and also thereare stack links between interface boards belonging to every other VD,respectively. As shown in FIG. 4, interface boards in both memberdevices 1 and 2 belonging to VD1 have stack link 1 between them,interface boards belonging to VD2 have stack link 2, interface boardsbelonging to VD3 have stack link 3, and interface boards belonging toVD4 have stack link 4.

At the startup of an IRF system, a managing VD is firstly created forimplementing VD allocation within the IRF system. Normally, VD1 is setas the managing VD by default. Specifically, the process of VDallocation includes: allocating each control board to at least two VDs;allocating each interface board to a VD among the at least two VDs;performing configuration for other VDs at the control boards and theinterface boards by the managing VD; and also configuring, for aninterface board which has been allocated to a VD, stack memberinterfaces of the VD that the interface board belongs to. The stackmember interfaces are used for connecting other stack member interfaceson another member device belonging to the same VD in order to establishstack links for the corresponding VD and to successfully forward servicemessages of the corresponding VD across member devices. In an exemplaryimplementation, a stack member interface can be a physical interface orlogical interface within an interface board.

During the service message forwarding across member devices, theinterface board needs to query a local forwarding table. The managing VDforms forwarding entries for a VD according to stack member interfacesof the VD and issues the forwarding entries to interface boardsbelonging to the corresponding VD in the IRF system.

In addition, the managing VD will designate multiple stack memberinterfaces in the same member device to form a stack port in order tofacilitate management of stack links and the stack member interfaces.

As shown in FIG. 4, when the IRF system starts up, VD1 is firstlycreated. It is assumed that the IRF system needs to be divided into fourVDs, the primary control board and the spare control board are to beused by VD1, VD2, VD3 and VD4. Each interface board is to be used by oneof the four VDs. Specifically, as to interface boards of a memberdevice, interface board 1 is designated for use by VD1, interface board2 is designated for use by VD2, interface board 3 is designated for useby VD3, and interface board 4 is designated for use by VD4. Each memberdevice in the IRF system can perform these configuration tasks.

In addition, a stack member interface for connecting a stack link isconfigured for each interface board that has been assigned a VD (in thisspecific implementation, the stack member interface can be a physicalstack interface). Per the example illustrated in FIG. 4, member device 1has physical stack interfaces P11, P12, P13 and P14, which arerespectively connected with physical stack interfaces P21, P22, P23 andP24 in member device 2, thus constituting stack link 1, stack link 2,stack link 3 and stack link 4, respectively.

In the example illustrated in FIG. 4, member devices each have both aprimary control board and spare control board. As another example,member devices having only a single control board can be used under theprinciples disclosed in the present disclosure.

For each member device, VD1 at the primary control board formsforwarding entries of a VD according to physical stack interfaces of theVD at each interface board and sends the forwarding entries to thecorresponding interface boards. In this way, interface boards 1 shown inFIG. 4 have forwarding entries of VD1 and are responsible for servicemessage transmission across member devices for VD1. Similarly, interfaceboards 2 have forwarding entries of VD2 and are responsible for servicemessage transmission across member devices for VD2; interface boards 3have forwarding entries of VD3 and are responsible for service messagetransmission across member devices for VD3; interface boards 4 haveforwarding entries of VD4 and are responsible for service messagetransmission across member devices for VD4.

It should be noted that, in addition to the situation shown in FIG. 4,multiple interface boards can also be allocated to a VD so that the VDcan have multiple stack links for transmitting service messages acrossmember devices. In this case, each interface board is equipped withforwarding entries of the corresponding VD so that either one cantransmit service messages across member devices for the correspondingVD.

When it is determined that transmission across member devices isrequired, a stack link set for the VD is selected for bearing a servicemessage to be transmitted through a query to the forwarding entries. Thestack link used for forwarding the service message to another memberdevice may not necessarily be the stack link connected to the interfaceboard that has received the service message from the VD. Alternatively,the message may be passed to another interface board corresponding tothe same VD for transmission. Thus, it can be a stack link connected toother interface boards belonging to the same VD as the interface boardthat has received the service message that ultimately transmits theservice message.

In FIG. 4, for example, if interface boards 1 and 2 in member device 1are allocated to VD1, and interface board 1 in member device 2 isallocated to VD1 for use, then interface board 1 in member device 2 canestablish stack links to both interface boards 1 and 2 in member device1. Alternatively, interface board 1 in member device 2 can establish astack link only with interface board 1 in member device 1 or only withinterface board 2 in member device 1.

In this example, when interface board 1 in member device 1 receives aservice message, it may provide the service message to interface board 2via an internal channel of member device 1. Thereafter, the servicemessage can be transmitted to member device 2 via a stack link betweeninterface board 2 of member device 1 and interface board 1 of memberdevice 2.

The physical stack interfaces P11, P12, P13 and P14 are all connectedwith member device 2, and the managing VD, i.e., VD1 at the primarycontrol board, configures P11, P12, P13 and P14 into a stack port on acontrol plane for control message forwarding. Thus, the stack port canbe called a control stack port. Similarly, P21, P22, P23 and P24 canalso be configured into a stack port.

Control message forwarding is implemented on the control plane based onan internal topology table of the IRF system, and all VDs share theinternal topology table within the IRF system. Each VD can use any stackmember interface included in the control stack port to transmit acontrol message across member devices. Thus, as long as a stack memberinterface included in the control stack port is in a normal connectingstate, control messages can be forwarded between member devicesproperly, thereby preventing stack unwinding of the member devices.Here, the control message may include: an inter-process communication(IPC) message, an STM message and so on.

The primary control board will provide configuration and managementinformation to spare control boards. Consequently, upon switchover fromthe primary control board to a spare control board, if needed, the sparecontrol board can take over the work of the primary control board toperform member device configuration and management.

Based on the above method, the present disclosure provides a memberdevice for forwarding traffic flow in an IRF system, where the memberdevice includes a control board and multiple interface boards. Thecontrol board is allocated to at least two VDs, and each interface boardis allocated to one of the at least two VDs. Also, there is a stack linkbetween a first interface board of the member device and a secondinterface board of another member device, where both interface boardsbelong to the same VD.

When an interface board receives a service message of the VD to whichthe interface board is allocated, forwarding entries stored in theinterface board are checked. If the service message needs to beforwarded across member devices, the interface board transmits theservice message through a stack link corresponding to the VD to whichthe interface board belongs.

The managing VD is created at the control board when the IRF systemstarts and is used for configuring other VDs at the control board andcorresponding interface boards. Here, each interface board in a memberdevice that has been assigned to a VD configures stack member interfacesfor that VD for forming stack links to transmit service messages forthat VD.

In a specific implementation of the present disclosure, control boardsin a member device may include: a primary control board and a sparecontrol board. Then, operations concerning configuration and managementof the member device are implemented by the managing VD at the primarycontrol board. Further, the managing VD at the control board uses stackmember interfaces to form forwarding entries of a VD (e.g., the managingVD or any other VD in the IRF system) the stack member interfaces belongto and issues the forwarding entries to interface boards of thecorresponding VD. In other words, the managing VD at the control boardis responsible for managing forwarding entries across member deviceswithin an IRF system, namely managing internal forwarding entries of theIRF system. Other VDs at the control board generate external forwardingentries for the IRF system and use service interfaces (i.e., externalinterfaces of the IRF system) to form the external forwarding entries.

The managing VD at the control board can define multiple stack memberinterfaces connected to the same member device as belonging to a controlstack port. Each VD sends control messages between member devices viaany stack member interface included in the control stack port. Controlmessages can be properly transmitted between member devices as long as astack member interface in the control stack port is normally connectedto a stack link in order to keep the stack of these member devices.

If a stack link is broken, causing the stack member interface connectedto the stack link to be down, the managing VD at the control board willdelete the stack member interface from a corresponding forwarding entry.

The internal structure of member device 1 or 2 as shown in FIG. 4 isonly illustrative of the possible structure of a member device. Otherconfigurations are possible.

It should be noted that, if more than one stack link is configured for acertain VD in the data plane, for example, there are multiple stackmember interfaces at interface boards of a member device belonging toVD1 connected with another member device, the multiple stack memberinterfaces configured for VD1 can be defined as a stack port in the dataplane for forwarding service messages of VD1. The stack port can also becalled a service stack port.

Traffic flow balance can be achieved by using a mode of nesting a stackport on stack member interfaces in the data plane when service messagesare to be transmitted across frames for the same VD. Here, an approachcan be used to nest the stack port on the stack member interfaces. Thus,when forming forwarding entries of each VD by use of stack memberinterfaces, an output interface of the forwarding entries may be aservice stack port of the VD and further be pointed to a number of stackmember interfaces included in the service stack port.

When a stack member interface is down, it is removed from the forwardingentries. When all the stack member interfaces included in the servicestack port of a VD are down, the service stack port is removed from theforwarding entries.

As can be seen from the above description, in the present disclosure,there is a stack link between interface boards of two member devicesbelonging to the same VD, which enables an interface board to forward aservice message via a stack link connected with the interface boardaccording to a forwarding entry stored in the interface board after theinterface board receives the service message of the VD to which theinterface board belongs. In this way, the traffic flow of different VDscan be forwarded between member devices of the IRF system.

In the case that more than two member devices in the IRF system have aninterface board belonging to the same VD, stack links with a chain orring shape can be established among these member devices. For example,if there are four member devices A-D allocated to VD1 in an IRF system,then at least one stack link can be established between member devices Aand B, member devices B and C, and member devices C and D, respectivelyto form a chain-shaped connection for VD1. Alternatively, at least onestack link can be established between member devices A and B, memberdevices B and C, member devices C and D, and member devices D and A,respectively to form a ring-shaped connection for VD1.

Thus, in each of the various examples given, a method and a memberdevice for forwarding traffic flow within an IRF system are provided.Consequently, the principles of the present specification enable trafficflow transmission across member devices for each VD of the IRF system.

A method for forwarding traffic flow in an Intelligent ResilientFramework (IRF) system is disclosed as an example. The method includes:allocating each member device in the IRF system to at least two virtualdevices and configuring at least one stack link for each virtual devicein order to connect interface boards among different member devices.When it is determined according to a forwarding entry of an interfaceboard in a first member device that receives a service message that theservice message is to be transmitted to a second member device, themethod includes forwarding the service message via the at least onestack link configured for the virtual device of the interface board.Specifically, each interface board is allocated to a particular VD foruse.

A member device in an Intelligent Resilient Framework (IRF) system isdisclosed as an example, which includes at least one control board andmultiple interface boards. Each control board is shared by multiplevirtual devices, while each interface board is allocated to a particularvirtual device among the multiple virtual devices. At least one stacklink is configured for each virtual device in order to connect interfaceboards corresponding to that virtual device between that member deviceand another member device in the IRF system.

In another example, a method for forwarding traffic flow within an IRFsystem is provided, which is applied in the IRF system including atleast two member devices. Each member device is allocated to at leasttwo virtual devices, and there is a stack link between interface boardsof the at least two member devices belonging to the same virtual device.When an interface board of a member device receives a service message ofthe VD to which that interface board belongs, forwarding entries of theinterface board are searched. When it is determined that the servicemessage is to be transmitted across member devices, the interface boardforwards the service message via a stack link of an interface boardcorresponding to that VD.

In another example, a member device for forwarding traffic flow withinan IRF system is provided, which is applied in an IRF system includingat least two member devices. The member device includes a control boardand interface boards. The control board is allocated to at least twovirtual devices, and each interface board is allocated to one of the atleast two virtual devices. There is a stack link between interfaceboards of the member device and another member device belonging to thesame virtual device. The interface board of the member device searchesforwarding entries of the interface board when it receives a servicemessage of the VD to which that interface board belongs. When theservice message is to be transmitted across member devices, theinterface board then forwards the service message via a stack linkcorresponding to the VD to which the interface board belongs.

It can be seen from the above technical solutions that at least onestack link is made to correspond to each VD between the two memberdevices in the present example. Then, an interface board of a memberdevice can use the stack link connected with that interface board itselfto forward a service message when the interface board receives theservice message of the VD to which the interface board belongs. Theinterface board forwards the service message according to forwardingentries stored in the interface board in order to achieve traffic flowforwarding across member devices for each VD in the IRF system.

In yet another example, an Intelligent Resilient Framework (IRF) systemis provided that includes at least two member devices. Each memberdevice is allocated to at least two virtual devices, and interfaceboards of different member devices are connected by at least one stacklink for each virtual device.

Each member device forwards a service message that is to be transmittedto another member device via the at least one stack link correspondingto the virtual device of the interface board receiving the servicemessage.

Further, the member device configures stack member interfaces connectingwith the at least one stack link of a virtual device into a servicestack port and transmits a service message of a virtual device toanother member device via any stack member interface included in theservice stack port for the virtual device.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings), may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention claimed is:
 1. A method for forwarding service messages inan Intelligent Resilient Framework (IRF) system, comprising: allocatingeach member device in the IRF system to at least two virtual devices,and configuring at least one stack link for each virtual device in orderto connect interface boards among different member devices; and when itis determined according to a forwarding entry of an interface board in afirst member device receiving a service message that the service messageis to be transmitted to a second member device, forwarding the servicemessage via the at least one stack link configured for the virtualdevice of that interface board.
 2. The method according to claim 1,further comprising: creating a managing virtual device at a controlboard of a member device during startup of the IRF system; and with themanaging virtual device, configuring other virtual devices at thecontrol board and interface boards of the IRF system, and configuring ateach interface board stack member interfaces for a virtual device towhich the interface board belongs for connecting corresponding stacklinks.
 3. The method according to claim 2, further comprising: with themanaging virtual device, generating forwarding entries of a virtualdevice according to stack member interfaces of the virtual device, andissuing the forwarding entries to the interface board of that virtualdevice.
 4. The method according to claim 3, further comprising: when astack link is disconnected and a stack member interface connected withthe stack link is down, deleting with the managing virtual device thestack member interface from a corresponding forwarding entry.
 5. Themethod according to claim 2, further comprising: with the managingvirtual device, configuring multiple stack member interfaces connectedwith a member device into a control stack port, and transmitting acontrol message to the member device via any stack member interfaceincluded in the control stack port for every virtual device.
 6. Themethod according to claim 2, further comprising: with the managingvirtual device, configuring multiple stack member interfaces in a memberdevice that are configured for a virtual device into a service stackport, and transmitting a service message to another member device viaany stack member interface included in the service stack port for thevirtual device.
 7. A member device in an Intelligent Resilient Framework(IRF) system, comprising: at least one control board and multipleinterface boards; wherein each control board is shared by multiplevirtual devices, each interface board is allocated to a virtual deviceamong the multiple virtual devices, and at least one stack link isconfigured for each virtual device in order to connect interface boardsbetween the member device and another member device in the IRF system;and each of the multiple interface boards is to receive a servicemessage of the virtual device to which that interface board corresponds,and forward the service message via the at least one stack linkconfigured for the virtual device to which that interface boardcorresponds if it is determined according to a forwarding entry of theinterface board that the service message is to be transmitted to theanother member device.
 8. The member device according to claim 7,further comprising: a managing virtual device set at the at least onecontrol board of the member device, to configure other virtual devicesat the at least one control board and the multiple interface boards, andconfigure, at each interface board, a stack member interface for avirtual device to which the interface board belongs for connectingcorresponding stack links.
 9. The member device according to claim 8,wherein the managing virtual device is further to: generate forwardingentries of a virtual device according to stack member interfaces of thevirtual device and issue the forwarding entries to the interface boardof the virtual device.
 10. The member device according to claim 9,wherein the managing virtual device is further to: delete a stack memberinterface from a corresponding forwarding entry when a correspondingstack link is disconnected and the stack member interface connected withthe stack link is down.
 11. The member device according to claim 8,wherein the managing virtual device is further to: configure multiplestack member interfaces of the member device which are connected with asecond member device into a control stack port, and transmit a controlmessage to the second member device via any stack member interfaceincluded in the control stack port for every virtual device in the IRFsystem.
 12. The member device according to claim 8, wherein the managingvirtual device is further to: configure multiple stack member interfacesof the member device that are configured for a virtual device into aservice stack port, and transmit a service message to another memberdevice via any stack member interface included in the service stack portfor the virtual device.
 13. An Intelligent Resilient Framework (IRF)system, comprising: at least two member devices; wherein each memberdevice is allocated to at least two virtual devices, and interfaceboards of different member devices are connected by at least one stacklink for each virtual device; and one of the member devices is toforward a service message to be transmitted to another member device viathe at least one stack link of an interface board corresponding to aparticular virtual device sending the service message.
 14. The systemaccording to claim 13, wherein at least one of the member devices isfurther to configure stack member interfaces connecting with the atleast one stack link of a virtual device into a service stack port, andtransmit a service message of a virtual device to another member devicevia any stack member interface included in the service stack port forthat virtual device.